Firefighters from Orono, Old Town and Milford extinguished the fire, which destroyed the trailer and its contents. The passing lane was reopened slightly more than two hours later, Trooper Trevor Snow of the Maine State Police said late Tuesday night.

Snow said the travel lane was expected to remain closed overnight to allow cleanup crews to remove sections of the trailer, which had so much damage that traditional wreckers could not be used.

The highway closure resulted in an interstate bottleneck that delayed travelers, Snow said.

Snow said the trailer that caught fire was owned by AJA Trading LLC of Broad Brook, Conn., and was heading to Hatfield, Mass., with a load of potatoes from Monticello.

The rig’s driver, Marc Benoit, 60, of Hampden, Mass., managed to save the cab by disengaging it from the trailer after the fire began. Benoit was not hurt, Snow said.

Snow said that an inspection by Trooper Joshua D’Angelo of the state police’s Commercial Vehicle Enforcement Unit indicated that the fire was the result of a mechanical problem involving one of the trailer’s wheels. Also assisting at the scene was Trooper Jonah O’Roak and Orono police.